With the development of man-machine interface technologies, touch sensing technologies that provide comfort and convenience in operation have been widely used. Especially in the field of consumer electronics such as notebook computers, mobile phones and MP3, a large number of touchpads, touch screens and touch buttons are used in such electronic products. Among the touch technologies, the capacitive touch technology is an advanced one, and typical applications thereof are, for example, iPad and iPhone. The detection principle of the capacitive touch technology is: identifying a touch state according to a small change in capacitance that occurs when a human body (or another object) approaches a detection electrode and changes the original electric field.
In the prior art, as shown in FIG. 1, a Smart Cover (cover) used on an iPad product is provided with a sensor that can sense a magnetic field, such as a Hall effect sensor, to wake up the screen or put the screen into a sleep state. When the Smart Cover is closed, the iPad enters the sleep state automatically. When the Smart Cover is opened, the iPad is immediately woken up without the need to press any button. Means of implementation is as follows: the Hall effect sensor generates a signal by sensing the presence of a magnetic field, the signal being used to change an operation state of a touch-screen electronic device, that is, when the Smart Cover approaches or moves away from the iPad, a magnetic field generated by an electric field element on the Smart Cover causes the Hall effect sensor to generate such a signal. However, for this method, an electric field element needs to be added into the cover, and a complex detection circuit needs to be provided in the iPad product.
The prior art is disadvantageous in that because an electric field element needs to be added into the cover and a corresponding detection circuit needs to be provided in the touch-screen electronic device, the costs cannot be reduced.